In many conduit applications, local building codes require that wires, particularly electrical wires, be enclosed in pipes or conduit, primarily for safety reasons. Conduit is typically made of a metal such as aluminum or steel and is sold commercially in straight pieces of various lengths.
In the course of installing conduit in or along a wall, it is necessary to bend the conduit to avoid doorways, ducts and other obstructions. An electrician can bend small-diameter, thinwall conduit by hand. Bending heavier conduits requires special bending tools and sometimes bending machines, including mechanical, hydraulic and electrically-powered machines.
A common conduit bending task is to form an “offset,” i.e., a pair of equal and opposite bends in a length of conduit such that the end portions of the conduit are parallel to, but offset from, each other. For example, where a conduit is to be installed horizontally in a wall, but a vent obstructs its path, an offset would be formed in the conduit so that, when installed, it passes by—either above or below—the obstruction, and resumes a horizontal orientation. Another conduit bending task is to form a “saddle.” A saddle consists of a first offset, a complementary offset, equal and opposite to the first offset. The saddle thus includes four bends, arranged such that a U-shaped detour is formed in the conduit to circumvent an obstruction.
It is critical that offsets and saddles be formed such that the entire length of the bent conduit lies in a plane so that, upon installation, the conduit fits inside or flush against the wall. If any bend after the first bend is made improperly, a section of the conduit will extend outside the plane. Such an errant section of pipe is known as a “wow” or “dogleg.” In other words, very accurate conduit bending is highly desired, and achieving accuracy in the bending of conduit can be challenging.
Conduit bending may be done on elaborate and expensive “bending tables.” Simpler bending machines also may be used, but all bending machines require “leveling” the conduit in the bending machine to form an offset or a saddle. “Leveling” means rotationally positioning the pipe relative to a reference plane, for example a horizontal plane, prior to forming each bend.
One method of leveling a conduit is sometimes called “eyeballing.” As the name implies, the operator simply uses his naked eyesight to view the bend after it is made to determine if a level position has been achieved. The method requires the operator to “eyeball” the bend from various angles and therefore is time consuming. Accuracy depends solely upon the skill of the operator and can be extremely poor if the operator's skills are low. Material loss and labor expense using this method can be very high.
Another known leveling method requires assembling a pair of locking pliers (for example, Vise-Grips), a length of square channel (“Kindorf”) stock, and a magnetic torpedo-type level. The operator applies the locking pliers to attach the channel stock to an open end of the conduit pipe to be bent. The magnetic torpedo level is then (magnetically) attached to the channel stock. The operator views the torpedo level to aid him or her in leveling the conduit relative to a horizontal plane.
The foregoing method is time consuming and unreliable. The orientation of the three detachable parts is critical, so that if any of them is bumped while bending the conduit, a dogleg is likely to result. The locking pliers are not a stable attachment means because the plier jaws do not fittingly engage the inside contour of the pipe to be bent. An inaccurate bend can result if the pliers shift during the bending process.
Another problem with this makeshift level is that the bubble level indicator in the torpedo level is not clearly visible from the position from which the operator makes the bends. The operator must move around the bending machine and the pipe being bent to adjust the bending direction. These added footsteps increase the time required for bending.
Certain prior tools for use in conduit bending only provide level vials facilitating so-called “no-dog” bending. The accuracy of the intended bending angle other than 90° is often determined by the operator's viewing of angle-registration marks on the head of a conduit-bending tool such as one seen in FIG. 18. Such method, can be very inaccurate and is heavily dependent on the operator's experience. In certain situations when several conduits need to be bent to a particular angle and remain parallel to each other, as seen in FIG. 17, a higher accuracy is desired.
Previously, the operators using a torpedo level have encountered difficulties related to visibility of the torpedo-level vials, as well as the need for observing a plurality of separate instruments. Accordingly, it too requires the operator frequently to move about in order to check for level positioning of the conduit preparatory to bending. This often results in inaccuracy and lost time.
It is desired to have an improved easy-to-use instrumentation for no-dog conduit bending and accurate indication of the intended bending angle with improved visibility of conduit-position indicators while facilitating time-efficient performance of conduit bending.